One possibility would be to design (and validate!) a series of long PCR amplicons to tile the gene (each one overlaps the previous one by a bit).

The pooled amplicons from each sample then generates a new fragment library. One thing to watch out for is that primer-derived sequences will have artificially high variant rates due to primer synthesis errors.

There is a long lange pcr kit offered by Qiagen. this kit will generate a library of 8 overlapped amplicons (10 kb each) for my 70 kb gene. I think i can use it and then with biorubter or covaris I can generate fragments with 200bp lenght for ePCR and sequencing afterward. What do you think....